ISBN 9783843945493

978-3-8439-4549-3, Reihe Physik

Fabian Böttcher
Supersolid Arrays of Dipolar Quantum Droplets

204 Seiten, Dissertation Universität Stuttgart (2020), Softcover, A5

Zusammenfassung / Abstract

In this thesis, we present the experimental realization of a new phase of matter, the elusive supersolid. This paradoxical phase of matter simultaneously combines the properties of a solid and a superfluid, properties that are normally thought of as mutually exclusive. Following extensive efforts to observe this exotic phase in helium, first signatures of supersolid properties were observed in experiments with ultra-cold quantum gases. However, in these experiments the density modulation was externally induced, leading to an incompressible solid without propagating phonon modes. Here, we use dipolar quantum gases where the constituent particles can interact via the short-range contact interaction and the long-range and anisotropic dipole-dipole interaction. The precise interplay of these two interactions in combination with the intrinsic quantum fluctuations leads to the emergence of liquid-like quantum droplets. Confining these quantum droplets leads to their fragmentation into arrays of multiple droplets, realizing a purely self-organized supersolid state of matter. Experimentally, we prove the supersolid nature of these droplet arrays by observing their characteristic periodic density modulation and global phase coherence, as well as the superfluid dynamics of the low-energy Goldstone and amplitude Higgs excitation modes.